[nsp-sec] List of vulnerable DNS resolvers

[Wayne Bogan]

ACK 2711, 6250

-----Original Message-----
From: nsp-security-bounces at puck.nether.net [mailto:nsp-security-bounces at puck.nether.net] On Behalf Of Niels Provos
Sent: Tuesday, July 22, 2008 7:12 PM
To: nsp-security at puck.nether.net
Subject: [nsp-sec] List of vulnerable DNS resolvers

----------- nsp-security Confidential --------

Hi,

as you know, the DNS flaw was leaked yesterday.   At the moment, ~70%
of all resolvers on the Internet use static or trivially predictable
source ports.   These resolvers/NAT devices need to be patched as soon
as possible.   The CERT reference for this flaw can be found at:

 http://www.kb.cert.org/vuls/id/800113

The flaw allows adversaries to inject almost arbitrary A or NS records
on vulnerable resolvers, e.g. redirect traffic/proxy traffic of
legitimate domains.

You can find a list of vulnerable resolvers and corresponding AS numbers at:

 https://asn.cymru.com/nsp-sec/upload/1216767459.whois.txt

These IP addresses are from recursive resolvers that showed very low
standard-deviation (<200) in their source ports according to
measurements conducted by David Dagon and myself over the last 7 days.
 I released a small Python tool that you can use to test your own
resolver.   You can download it from:

  http://www.monkey.org/~provos/dnspredict.py

Instructions on how to use the tool can be found here:

 http://www.provos.org/index.php?/archives/42-DNS-and-Randomness.html

Please, let me know if you have any questions.

Thank you,
 Niels.


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